IMO Shortlist 2012, Combinatorics 2
Source: IMO Shortlist 2012, Combinatorics 2
July 29, 2013
IMO ShortlistcombinatoricsExtremal combinatoricsDoublecounting
Problem Statement
Let be an integer. What is the maximum number of disjoint pairs of elements of the set such that the sums of the different pairs are different integers not exceeding ?